Acoustic design tools for estimation of sound insulation performance of wood wall and floor assemblies

The National Building Code of Canada 2015 stipulates the minimum requirements of the airborne sound insulation transmission through common interior walls and ceiling/floor assemblies. The required minimum Apparent Sound Transmission Class (ASTC) is 47 in Canada, whereas the Impact Insulation Class (IIC) for floors is recommended to be higher than 55. For many years, significant efforts were made to develop sound insulation prediction models or tools to predict the sound insulation performance of wall and floor/ceiling assemblies at the design phase in order to meet the requirements and the recommendations made by codes. However, today few models can provide a reliable acoustics design tool. In this document, three prediction tools thought to be practically useful are presented and evaluated. Between these three prediction tools, one is an analytical model of the Insul software while the other two are empirical models developed by the National Research Council of Canada and the American Wood Council. This paper compared the STC and IIC ratings of wood wall and floor assemblies estimated by these three models and verified them by the measured STC and IIC ratings. This work aims at providing an idea for readers to choose a suitable design tool to proceed with their acoustic designs.

Acoustical performance of horizontal-sliding-panel operable partition walls

Field measurements of airborne sound transmission loss were made on several operable partitions of the horizontal-sliding-panel type between conference rooms. Apparent Sound Transmission Class (ASTC) and Noise Isolation Class (NIC) ratings were computed. Very significant deviation of field-measured sound transmission ratings and manufacturers' Sound Transmission Class (STC) ratings were found. Clients were not satisfied by actual sound isolating performance. Transmission of voice was clearly audible. Some deficiencies of field conditions were found. Some deficiencies of partition installation were found. Modifications were made; acoustical performance did not change significantly.

The effects of acoustical ceiling panel type and penetrations for services on vertical sound isolation inside buildings

Attenuation of sound transmitting between rooms oriented over one another inside buildings is studied. Transmission loss and sound transmission class were measured by an independent, accredited, acoustics laboratory with and without a variety of modular acoustic ceilings suspended under a baseline concrete floor structure. Ceiling panel material types include stone wool, fiberglass and mineral fiber. Ceilings were tested with and without the presence of service penetrations for supply air diffusers, return air grilles and light fixtures. Some ceilings were also scanned with a sound intensity probe and the resulting color sound maps are used as a supplemental method of evaluating both isolation and absorption performance of the individual components of the ceiling systems. Results show that while the effects of ceiling panel type on absorption performance, and thus room acoustics, is substantial, the material type and weight of the ceiling panels do not substantially affect the overall isolation performance of the floor-ceiling assembly.

A case study in the measurement of door sound isolation with ASTM test standards

The use of the door transmission class rating in lieu of the apparent sound transmission class rating has yet to gain traction within building codes and specified project requirements. This paper presents a case study involving performance requirement testing conducted at a university's media facility, in which sound insulation properties were a critical design and construction focus. Both test methods described in ASTM E2964 and ASTM E336 were performed where a door was the test partition. Door transmission class ratings were presented in comparison to apparent sound transmission class ratings for the same partition. Testing was performed in a variety of situations, including scenarios both inside and outside of the minimum requirements of testing standards. Our analysis considers the effectiveness of the recently adopted ASTM E2964 in comparison to the methods of the ASTM E336. We also consider some of the subtle differences between the two test methods and how they may impact the testing of certain adjacencies.

Enhanced speech privacy in office spaces

There is an ever-increasing demand for speech privacy in modern office spaces. People prefer their conversations to remain private while not being disturbed by speech of others. The work presented in this article focuses on reducing the intelligibility of the perceived speech by masking the original signal without a significant additional annoyance. The disruption of the information-carrying components of speech by the amplitude and temporal smearing is of a specific interest of this work. We suggest a method in which a modified self-adjusted masking signal is used to effectively counteract the drawbacks of a straightforward reverberation. The presented masking method disrupts key speech characteristics of the original signal. The intelligibility and annoyance levels of the resulting signal are subjectively evaluated. The optimized experimental parameters are reported. The presented method provides a significantly higher speech privacy and a lower perceived annoyance as compared to white noise. The method can be used in office environments with various Sound Transmission Class levels.